Journal or Book Title
The F′ band has been produced and measured in the following alkali halides: NaCl, KCl, KBr, KI, RbCl, RbI, CsBr, and CsI. Additively colored samples were optically bleached in the F band at an optimum temperature to produce a maximum F-to-F′ conversion. The observed spectra exhibited two distinctive features. In each salt the F′ band had a shoulder on the high-energy side of the principal peak, except in NaCl where the band was bell-shaped. CsBr and CsI exhibited a more complex structure. The shoulder in the potassium and rubidium salts is attributed to low-lying d-like states in their conduction-band structure. In all salts there was a small second absorption shoulder on the high-energy tail of the F′ band. This absorption is attributed to F′ absorption such that the remaining F center is left in an excited 2por 2s state. A semicontinuum-model variational calculation using a correlated Hylleraas wave function yields, for reasonable values of the parameters, F′ binding energies in fair agreement with the observed optical absorption edges. An absorption-cross-section calculation yields absorption curves in good agreement with experiment if one excludes the aforementioned structure.
The American Physical Society
Lynch, David W. and Robinson, David Atherton, "Study of the F′ Center in Several Alkali Halides" (1968). Physics and Astronomy Publications. 16.